1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * SM4-CCM AEAD Algorithm using ARMv8 Crypto Extensions
4 * as specified in rfc8998
5 * https://datatracker.ietf.org/doc/html/rfc8998
6 *
7 * Copyright (C) 2022 Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
8 */
9
10 #include <linux/module.h>
11 #include <linux/crypto.h>
12 #include <linux/kernel.h>
13 #include <linux/cpufeature.h>
14 #include <asm/neon.h>
15 #include <crypto/scatterwalk.h>
16 #include <crypto/internal/aead.h>
17 #include <crypto/internal/skcipher.h>
18 #include <crypto/sm4.h>
19 #include "sm4-ce.h"
20
21 asmlinkage void sm4_ce_cbcmac_update(const u32 *rkey_enc, u8 *mac,
22 const u8 *src, unsigned int nblocks);
23 asmlinkage void sm4_ce_ccm_enc(const u32 *rkey_enc, u8 *dst, const u8 *src,
24 u8 *iv, unsigned int nbytes, u8 *mac);
25 asmlinkage void sm4_ce_ccm_dec(const u32 *rkey_enc, u8 *dst, const u8 *src,
26 u8 *iv, unsigned int nbytes, u8 *mac);
27 asmlinkage void sm4_ce_ccm_final(const u32 *rkey_enc, u8 *iv, u8 *mac);
28
29
30 static int ccm_setkey(struct crypto_aead *tfm, const u8 *key,
31 unsigned int key_len)
32 {
33 struct sm4_ctx *ctx = crypto_aead_ctx(tfm);
34
35 if (key_len != SM4_KEY_SIZE)
36 return -EINVAL;
37
38 kernel_neon_begin();
39 sm4_ce_expand_key(key, ctx->rkey_enc, ctx->rkey_dec,
40 crypto_sm4_fk, crypto_sm4_ck);
41 kernel_neon_end();
42
43 return 0;
44 }
45
46 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
47 {
48 if ((authsize & 1) || authsize < 4)
49 return -EINVAL;
50 return 0;
51 }
52
53 static int ccm_format_input(u8 info[], struct aead_request *req,
54 unsigned int msglen)
55 {
56 struct crypto_aead *aead = crypto_aead_reqtfm(req);
57 unsigned int l = req->iv[0] + 1;
58 unsigned int m;
59 __be32 len;
60
61 /* verify that CCM dimension 'L': 2 <= L <= 8 */
62 if (l < 2 || l > 8)
63 return -EINVAL;
64 if (l < 4 && msglen >> (8 * l))
65 return -EOVERFLOW;
66
67 memset(&req->iv[SM4_BLOCK_SIZE - l], 0, l);
68
69 memcpy(info, req->iv, SM4_BLOCK_SIZE);
70
71 m = crypto_aead_authsize(aead);
72
73 /* format flags field per RFC 3610/NIST 800-38C */
74 *info |= ((m - 2) / 2) << 3;
75 if (req->assoclen)
76 *info |= (1 << 6);
77
78 /*
79 * format message length field,
80 * Linux uses a u32 type to represent msglen
81 */
82 if (l >= 4)
83 l = 4;
84
85 len = cpu_to_be32(msglen);
86 memcpy(&info[SM4_BLOCK_SIZE - l], (u8 *)&len + 4 - l, l);
87
88 return 0;
89 }
90
91 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
92 {
93 struct crypto_aead *aead = crypto_aead_reqtfm(req);
94 struct sm4_ctx *ctx = crypto_aead_ctx(aead);
95 struct __packed { __be16 l; __be32 h; } aadlen;
96 u32 assoclen = req->assoclen;
97 struct scatter_walk walk;
98 unsigned int len;
99
100 if (assoclen < 0xff00) {
101 aadlen.l = cpu_to_be16(assoclen);
102 len = 2;
103 } else {
104 aadlen.l = cpu_to_be16(0xfffe);
105 put_unaligned_be32(assoclen, &aadlen.h);
106 len = 6;
107 }
108
109 sm4_ce_crypt_block(ctx->rkey_enc, mac, mac);
110 crypto_xor(mac, (const u8 *)&aadlen, len);
111
112 scatterwalk_start(&walk, req->src);
113
114 do {
115 u32 n = scatterwalk_clamp(&walk, assoclen);
116 u8 *p, *ptr;
117
118 if (!n) {
119 scatterwalk_start(&walk, sg_next(walk.sg));
120 n = scatterwalk_clamp(&walk, assoclen);
121 }
122
123 p = ptr = scatterwalk_map(&walk);
124 assoclen -= n;
125 scatterwalk_advance(&walk, n);
126
127 while (n > 0) {
128 unsigned int l, nblocks;
129
130 if (len == SM4_BLOCK_SIZE) {
131 if (n < SM4_BLOCK_SIZE) {
132 sm4_ce_crypt_block(ctx->rkey_enc,
133 mac, mac);
134
135 len = 0;
136 } else {
137 nblocks = n / SM4_BLOCK_SIZE;
138 sm4_ce_cbcmac_update(ctx->rkey_enc,
139 mac, ptr, nblocks);
140
141 ptr += nblocks * SM4_BLOCK_SIZE;
142 n %= SM4_BLOCK_SIZE;
143
144 continue;
145 }
146 }
147
148 l = min(n, SM4_BLOCK_SIZE - len);
149 if (l) {
150 crypto_xor(mac + len, ptr, l);
151 len += l;
152 ptr += l;
153 n -= l;
154 }
155 }
156
157 scatterwalk_unmap(p);
158 scatterwalk_done(&walk, 0, assoclen);
159 } while (assoclen);
160 }
161
162 static int ccm_crypt(struct aead_request *req, struct skcipher_walk *walk,
163 u32 *rkey_enc, u8 mac[],
164 void (*sm4_ce_ccm_crypt)(const u32 *rkey_enc, u8 *dst,
165 const u8 *src, u8 *iv,
166 unsigned int nbytes, u8 *mac))
167 {
168 u8 __aligned(8) ctr0[SM4_BLOCK_SIZE];
169 int err = 0;
170
171 /* preserve the initial ctr0 for the TAG */
172 memcpy(ctr0, walk->iv, SM4_BLOCK_SIZE);
173 crypto_inc(walk->iv, SM4_BLOCK_SIZE);
174
175 kernel_neon_begin();
176
177 if (req->assoclen)
178 ccm_calculate_auth_mac(req, mac);
179
180 while (walk->nbytes && walk->nbytes != walk->total) {
181 unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE;
182
183 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
184 walk->src.virt.addr, walk->iv,
185 walk->nbytes - tail, mac);
186
187 kernel_neon_end();
188
189 err = skcipher_walk_done(walk, tail);
190
191 kernel_neon_begin();
192 }
193
194 if (walk->nbytes) {
195 sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
196 walk->src.virt.addr, walk->iv,
197 walk->nbytes, mac);
198
199 sm4_ce_ccm_final(rkey_enc, ctr0, mac);
200
201 kernel_neon_end();
202
203 err = skcipher_walk_done(walk, 0);
204 } else {
205 sm4_ce_ccm_final(rkey_enc, ctr0, mac);
206
207 kernel_neon_end();
208 }
209
210 return err;
211 }
212
213 static int ccm_encrypt(struct aead_request *req)
214 {
215 struct crypto_aead *aead = crypto_aead_reqtfm(req);
216 struct sm4_ctx *ctx = crypto_aead_ctx(aead);
217 u8 __aligned(8) mac[SM4_BLOCK_SIZE];
218 struct skcipher_walk walk;
219 int err;
220
221 err = ccm_format_input(mac, req, req->cryptlen);
222 if (err)
223 return err;
224
225 err = skcipher_walk_aead_encrypt(&walk, req, false);
226 if (err)
227 return err;
228
229 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_enc);
230 if (err)
231 return err;
232
233 /* copy authtag to end of dst */
234 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
235 crypto_aead_authsize(aead), 1);
236
237 return 0;
238 }
239
240 static int ccm_decrypt(struct aead_request *req)
241 {
242 struct crypto_aead *aead = crypto_aead_reqtfm(req);
243 unsigned int authsize = crypto_aead_authsize(aead);
244 struct sm4_ctx *ctx = crypto_aead_ctx(aead);
245 u8 __aligned(8) mac[SM4_BLOCK_SIZE];
246 u8 authtag[SM4_BLOCK_SIZE];
247 struct skcipher_walk walk;
248 int err;
249
250 err = ccm_format_input(mac, req, req->cryptlen - authsize);
251 if (err)
252 return err;
253
254 err = skcipher_walk_aead_decrypt(&walk, req, false);
255 if (err)
256 return err;
257
258 err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_dec);
259 if (err)
260 return err;
261
262 /* compare calculated auth tag with the stored one */
263 scatterwalk_map_and_copy(authtag, req->src,
264 req->assoclen + req->cryptlen - authsize,
265 authsize, 0);
266
267 if (crypto_memneq(authtag, mac, authsize))
268 return -EBADMSG;
269
270 return 0;
271 }
272
273 static struct aead_alg sm4_ccm_alg = {
274 .base = {
275 .cra_name = "ccm(sm4)",
276 .cra_driver_name = "ccm-sm4-ce",
277 .cra_priority = 400,
278 .cra_blocksize = 1,
279 .cra_ctxsize = sizeof(struct sm4_ctx),
280 .cra_module = THIS_MODULE,
281 },
282 .ivsize = SM4_BLOCK_SIZE,
283 .chunksize = SM4_BLOCK_SIZE,
284 .maxauthsize = SM4_BLOCK_SIZE,
285 .setkey = ccm_setkey,
286 .setauthsize = ccm_setauthsize,
287 .encrypt = ccm_encrypt,
288 .decrypt = ccm_decrypt,
289 };
290
291 static int __init sm4_ce_ccm_init(void)
292 {
293 return crypto_register_aead(&sm4_ccm_alg);
294 }
295
296 static void __exit sm4_ce_ccm_exit(void)
297 {
298 crypto_unregister_aead(&sm4_ccm_alg);
299 }
300
301 module_cpu_feature_match(SM4, sm4_ce_ccm_init);
302 module_exit(sm4_ce_ccm_exit);
303
304 MODULE_DESCRIPTION("Synchronous SM4 in CCM mode using ARMv8 Crypto Extensions");
305 MODULE_ALIAS_CRYPTO("ccm(sm4)");
306 MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>");
307 MODULE_LICENSE("GPL v2");
308
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